Development of picosecond (ps) and femtosecond (fs) optical pulses has opened many areas of physics, chemistry and biology to experimental investigation. Lasers have also been tools for electron acceleration, and ultra short (&lt;10 ps), high power laser pulses have found many uses in the just-mentioned fields.
However, in order to fully utilize such pulses, they must be temporally characterized to a high degree of accuracy. In the past, this characterization has been by optical autocorrelation, see "Single-shot measurement of a 52-fs pulse," by F. Salin, et al., published in Applied Optics, volume 26, No. 21, Nov. 1, 1987, pp. 4528-4531, "Versatile Single-Shot Background-Free Pulse Duration Measurement Technique, for Pulses of Subnanosecond to Picosecond Duration," by R. Wyatt and E. B. Marinero, published in Applied Physics, volume 25, 297-301 (1981). Other techniques that have been used include the use of special cameras and the like.
Known techniques have the disadvantage of being time-intensive, and often require data points from fifty or more separate laser pulses in order to map out a pulse profile. These techniques generally cannot be carried out in a real-time, on-line manner. Still further, these techniques often cannot be used to characterize every pulse in a monitored system.
Still further, the high energy of these pulses can make measurement difficult since the pulses may tend to degrade any measuring device used.
Yet a further means for measuring sub-nanosecond laser pulses can include a reflection switch used as a sampling gate. This means includes two sampling gates. Pulses are propagated past one of the sampling gates, and that gate is altered until a pulse is intercepted by the gate. Then, further pulses are propagated past the other sampling gate until a pulse is intercepted by that second sampling gate. The spacing between the two sampling gates is measured, and that spacing represents the width of the pulse. As can be understood from the foregoing description, a pulselength measuring technique using this sampling gate means is tedious and indirect.
Therefore, there is a need for an improved means and a method for measuring ultra short, high energy laser pulses. There is a further need for a means and a method for measuring such ultra short, high energy laser pulses in an on-line, real time manner, which means and method provides the capability of measuring every pulse in a monitored system.